Study Notes
Light and sound are forms of waves that exhibit various behaviors such as reflection, refraction, and transmission through different media.
- Law of Reflection — states that the angle of incidence is equal to the angle of reflection. Example: A light ray hitting a mirror at 30° will reflect off at 30°.
- Incident Ray — the light ray that hits a surface. Example: The light from a flashlight hitting a mirror.
- Reflected Ray — the light ray that bounces off a surface. Example: The light seen in a mirror.
- Normal — a line perpendicular to the surface at the point of incidence. Example: An imaginary line at a 90° angle to the mirror.
- Refraction — the bending of light as it passes from one medium to another. Example: A straw appearing bent in a glass of water.
- Refractive Index — a measure of how much light slows down in a medium. Example: Glass has a refractive index of about 1.5.
- Total Internal Reflection — occurs when light cannot exit a medium and is completely reflected inside. Example: Light trapped inside a glass fiber.
- Sound Waves — longitudinal waves that require a medium to travel. Example: Sound traveling through air at 330 m/s.
Exam Tips
Key Definitions to Remember
- Law of Reflection: Angle of incidence equals angle of reflection.
- Refraction: Bending of light when it enters a different medium.
- Total Internal Reflection: Complete reflection of light within a medium.
- Refractive Index: Ratio of speed of light in vacuum to speed in a medium.
- Sound Waves: Longitudinal waves requiring a medium.
Common Confusions
- Mixing up angle of incidence and angle of reflection.
- Forgetting that sound cannot travel in a vacuum.
- Confusing refraction with reflection.
Typical Exam Questions
- What is the law of reflection? The angle of incidence equals the angle of reflection.
- How does light behave when it enters a denser medium? It bends towards the normal.
- What is total internal reflection? Light is completely reflected inside a medium when the angle of incidence exceeds the critical angle.
What Examiners Usually Test
- Understanding of light behavior at boundaries.
- Ability to calculate refractive index.
- Differences between longitudinal and transverse waves.